1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * Authors: Lotsa people, from code originally in tcp
8 */
9
10#ifndef _INET_HASHTABLES_H
11#define _INET_HASHTABLES_H
12
13
14#include <linux/interrupt.h>
15#include <linux/ip.h>
16#include <linux/ipv6.h>
17#include <linux/list.h>
18#include <linux/slab.h>
19#include <linux/socket.h>
20#include <linux/spinlock.h>
21#include <linux/types.h>
22#include <linux/wait.h>
23
24#include <net/inet_connection_sock.h>
25#include <net/inet_sock.h>
26#include <net/ip.h>
27#include <net/sock.h>
28#include <net/route.h>
29#include <net/tcp_states.h>
30#include <net/netns/hash.h>
31
32#include <linux/refcount.h>
33#include <asm/byteorder.h>
34
35/* This is for all connections with a full identity, no wildcards.
36 * The 'e' prefix stands for Establish, but we really put all sockets
37 * but LISTEN ones.
38 */
39struct inet_ehash_bucket {
40 struct hlist_nulls_head chain;
41};
42
43/* There are a few simple rules, which allow for local port reuse by
44 * an application. In essence:
45 *
46 * 1) Sockets bound to different interfaces may share a local port.
47 * Failing that, goto test 2.
48 * 2) If all sockets have sk->sk_reuse set, and none of them are in
49 * TCP_LISTEN state, the port may be shared.
50 * Failing that, goto test 3.
51 * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local
52 * address, and none of them are the same, the port may be
53 * shared.
54 * Failing this, the port cannot be shared.
55 *
56 * The interesting point, is test #2. This is what an FTP server does
57 * all day. To optimize this case we use a specific flag bit defined
58 * below. As we add sockets to a bind bucket list, we perform a
59 * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN))
60 * As long as all sockets added to a bind bucket pass this test,
61 * the flag bit will be set.
62 * The resulting situation is that tcp_v[46]_verify_bind() can just check
63 * for this flag bit, if it is set and the socket trying to bind has
64 * sk->sk_reuse set, we don't even have to walk the owners list at all,
65 * we return that it is ok to bind this socket to the requested local port.
66 *
67 * Sounds like a lot of work, but it is worth it. In a more naive
68 * implementation (ie. current FreeBSD etc.) the entire list of ports
69 * must be walked for each data port opened by an ftp server. Needless
70 * to say, this does not scale at all. With a couple thousand FTP
71 * users logged onto your box, isn't it nice to know that new data
72 * ports are created in O(1) time? I thought so. ;-) -DaveM
73 */
74#define FASTREUSEPORT_ANY 1
75#define FASTREUSEPORT_STRICT 2
76
77struct inet_bind_bucket {
78 possible_net_t ib_net;
79 int l3mdev;
80 unsigned short port;
81 signed char fastreuse;
82 signed char fastreuseport;
83 kuid_t fastuid;
84#if IS_ENABLED(CONFIG_IPV6)
85 struct in6_addr fast_v6_rcv_saddr;
86#endif
87 __be32 fast_rcv_saddr;
88 unsigned short fast_sk_family;
89 bool fast_ipv6_only;
90 struct hlist_node node;
91 struct hlist_head bhash2;
92 struct rcu_head rcu;
93};
94
95struct inet_bind2_bucket {
96 possible_net_t ib_net;
97 int l3mdev;
98 unsigned short port;
99#if IS_ENABLED(CONFIG_IPV6)
100 unsigned short addr_type;
101 struct in6_addr v6_rcv_saddr;
102#define rcv_saddr v6_rcv_saddr.s6_addr32[3]
103#else
104 __be32 rcv_saddr;
105#endif
106 /* Node in the bhash2 inet_bind_hashbucket chain */
107 struct hlist_node node;
108 struct hlist_node bhash_node;
109 /* List of sockets hashed to this bucket */
110 struct hlist_head owners;
111 signed char fastreuse;
112 signed char fastreuseport;
113};
114
115static inline struct net *ib_net(const struct inet_bind_bucket *ib)
116{
117 return read_pnet(pnet: &ib->ib_net);
118}
119
120static inline struct net *ib2_net(const struct inet_bind2_bucket *ib)
121{
122 return read_pnet(pnet: &ib->ib_net);
123}
124
125#define inet_bind_bucket_for_each(tb, head) \
126 hlist_for_each_entry(tb, head, node)
127
128struct inet_bind_hashbucket {
129 spinlock_t lock;
130 struct hlist_head chain;
131};
132
133/* Sockets can be hashed in established or listening table.
134 * We must use different 'nulls' end-of-chain value for all hash buckets :
135 * A socket might transition from ESTABLISH to LISTEN state without
136 * RCU grace period. A lookup in ehash table needs to handle this case.
137 */
138#define LISTENING_NULLS_BASE (1U << 29)
139struct inet_listen_hashbucket {
140 spinlock_t lock;
141 struct hlist_nulls_head nulls_head;
142};
143
144/* This is for listening sockets, thus all sockets which possess wildcards. */
145#define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */
146
147struct inet_hashinfo {
148 /* This is for sockets with full identity only. Sockets here will
149 * always be without wildcards and will have the following invariant:
150 *
151 * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE
152 *
153 */
154 struct inet_ehash_bucket *ehash;
155 spinlock_t *ehash_locks;
156 unsigned int ehash_mask;
157 unsigned int ehash_locks_mask;
158
159 /* Ok, let's try this, I give up, we do need a local binding
160 * TCP hash as well as the others for fast bind/connect.
161 */
162 struct kmem_cache *bind_bucket_cachep;
163 /* This bind table is hashed by local port */
164 struct inet_bind_hashbucket *bhash;
165 struct kmem_cache *bind2_bucket_cachep;
166 /* This bind table is hashed by local port and sk->sk_rcv_saddr (ipv4)
167 * or sk->sk_v6_rcv_saddr (ipv6). This 2nd bind table is used
168 * primarily for expediting bind conflict resolution.
169 */
170 struct inet_bind_hashbucket *bhash2;
171 unsigned int bhash_size;
172
173 /* The 2nd listener table hashed by local port and address */
174 unsigned int lhash2_mask;
175 struct inet_listen_hashbucket *lhash2;
176
177 bool pernet;
178} ____cacheline_aligned_in_smp;
179
180static inline struct inet_hashinfo *tcp_get_hashinfo(const struct sock *sk)
181{
182 return sock_net(sk)->ipv4.tcp_death_row.hashinfo;
183}
184
185static inline struct inet_listen_hashbucket *
186inet_lhash2_bucket(struct inet_hashinfo *h, u32 hash)
187{
188 return &h->lhash2[hash & h->lhash2_mask];
189}
190
191static inline struct inet_ehash_bucket *inet_ehash_bucket(
192 struct inet_hashinfo *hashinfo,
193 unsigned int hash)
194{
195 return &hashinfo->ehash[hash & hashinfo->ehash_mask];
196}
197
198static inline spinlock_t *inet_ehash_lockp(
199 struct inet_hashinfo *hashinfo,
200 unsigned int hash)
201{
202 return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
203}
204
205int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
206
207static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
208{
209 kvfree(addr: hashinfo->ehash_locks);
210 hashinfo->ehash_locks = NULL;
211}
212
213struct inet_hashinfo *inet_pernet_hashinfo_alloc(struct inet_hashinfo *hashinfo,
214 unsigned int ehash_entries);
215void inet_pernet_hashinfo_free(struct inet_hashinfo *hashinfo);
216
217struct inet_bind_bucket *
218inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
219 struct inet_bind_hashbucket *head,
220 const unsigned short snum, int l3mdev);
221void inet_bind_bucket_destroy(struct inet_bind_bucket *tb);
222
223bool inet_bind_bucket_match(const struct inet_bind_bucket *tb,
224 const struct net *net, unsigned short port,
225 int l3mdev);
226
227struct inet_bind2_bucket *
228inet_bind2_bucket_create(struct kmem_cache *cachep, struct net *net,
229 struct inet_bind_hashbucket *head,
230 struct inet_bind_bucket *tb,
231 const struct sock *sk);
232
233void inet_bind2_bucket_destroy(struct kmem_cache *cachep,
234 struct inet_bind2_bucket *tb);
235
236struct inet_bind2_bucket *
237inet_bind2_bucket_find(const struct inet_bind_hashbucket *head,
238 const struct net *net,
239 unsigned short port, int l3mdev,
240 const struct sock *sk);
241
242bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb,
243 const struct net *net, unsigned short port,
244 int l3mdev, const struct sock *sk);
245
246static inline u32 inet_bhashfn(const struct net *net, const __u16 lport,
247 const u32 bhash_size)
248{
249 return (lport + net_hash_mix(net)) & (bhash_size - 1);
250}
251
252static inline struct inet_bind_hashbucket *
253inet_bhashfn_portaddr(const struct inet_hashinfo *hinfo, const struct sock *sk,
254 const struct net *net, unsigned short port)
255{
256 u32 hash;
257
258#if IS_ENABLED(CONFIG_IPV6)
259 if (sk->sk_family == AF_INET6)
260 hash = ipv6_portaddr_hash(net, addr6: &sk->sk_v6_rcv_saddr, port);
261 else
262#endif
263 hash = ipv4_portaddr_hash(net, saddr: sk->sk_rcv_saddr, port);
264 return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)];
265}
266
267struct inet_bind_hashbucket *
268inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, int port);
269
270/* This should be called whenever a socket's sk_rcv_saddr (ipv4) or
271 * sk_v6_rcv_saddr (ipv6) changes after it has been binded. The socket's
272 * rcv_saddr field should already have been updated when this is called.
273 */
274int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family);
275void inet_bhash2_reset_saddr(struct sock *sk);
276
277void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
278 struct inet_bind2_bucket *tb2, unsigned short port);
279
280/* Caller must disable local BH processing. */
281int __inet_inherit_port(const struct sock *sk, struct sock *child);
282
283void inet_put_port(struct sock *sk);
284
285void inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
286 unsigned long numentries, int scale,
287 unsigned long low_limit,
288 unsigned long high_limit);
289int inet_hashinfo2_init_mod(struct inet_hashinfo *h);
290
291bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk);
292bool inet_ehash_nolisten(struct sock *sk, struct sock *osk,
293 bool *found_dup_sk);
294int inet_hash(struct sock *sk);
295void inet_unhash(struct sock *sk);
296
297struct sock *__inet_lookup_listener(const struct net *net,
298 struct sk_buff *skb, int doff,
299 const __be32 saddr, const __be16 sport,
300 const __be32 daddr,
301 const unsigned short hnum,
302 const int dif, const int sdif);
303
304static inline struct sock *inet_lookup_listener(struct net *net,
305 struct sk_buff *skb, int doff,
306 __be32 saddr, __be16 sport,
307 __be32 daddr, __be16 dport,
308 int dif, int sdif)
309{
310 return __inet_lookup_listener(net, skb, doff, saddr, sport,
311 daddr, ntohs(dport), dif, sdif);
312}
313
314/* Socket demux engine toys. */
315/* What happens here is ugly; there's a pair of adjacent fields in
316 struct inet_sock; __be16 dport followed by __u16 num. We want to
317 search by pair, so we combine the keys into a single 32bit value
318 and compare with 32bit value read from &...->dport. Let's at least
319 make sure that it's not mixed with anything else...
320 On 64bit targets we combine comparisons with pair of adjacent __be32
321 fields in the same way.
322*/
323#ifdef __BIG_ENDIAN
324#define INET_COMBINED_PORTS(__sport, __dport) \
325 ((__force __portpair)(((__force __u32)(__be16)(__sport) << 16) | (__u32)(__dport)))
326#else /* __LITTLE_ENDIAN */
327#define INET_COMBINED_PORTS(__sport, __dport) \
328 ((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
329#endif
330
331#ifdef __BIG_ENDIAN
332#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
333 const __addrpair __name = (__force __addrpair) ( \
334 (((__force __u64)(__be32)(__saddr)) << 32) | \
335 ((__force __u64)(__be32)(__daddr)))
336#else /* __LITTLE_ENDIAN */
337#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
338 const __addrpair __name = (__force __addrpair) ( \
339 (((__force __u64)(__be32)(__daddr)) << 32) | \
340 ((__force __u64)(__be32)(__saddr)))
341#endif /* __BIG_ENDIAN */
342
343static inline bool inet_match(const struct net *net, const struct sock *sk,
344 const __addrpair cookie, const __portpair ports,
345 int dif, int sdif)
346{
347 if (!net_eq(net1: sock_net(sk), net2: net) ||
348 sk->sk_portpair != ports ||
349 sk->sk_addrpair != cookie)
350 return false;
351
352 /* READ_ONCE() paired with WRITE_ONCE() in sock_bindtoindex_locked() */
353 return inet_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif,
354 sdif);
355}
356
357/* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
358 * not check it for lookups anymore, thanks Alexey. -DaveM
359 */
360struct sock *__inet_lookup_established(const struct net *net,
361 const __be32 saddr, const __be16 sport,
362 const __be32 daddr, const u16 hnum,
363 const int dif, const int sdif);
364
365typedef u32 (inet_ehashfn_t)(const struct net *net,
366 const __be32 laddr, const __u16 lport,
367 const __be32 faddr, const __be16 fport);
368
369inet_ehashfn_t inet_ehashfn;
370
371INDIRECT_CALLABLE_DECLARE(inet_ehashfn_t udp_ehashfn);
372
373struct sock *inet_lookup_reuseport(const struct net *net, struct sock *sk,
374 struct sk_buff *skb, int doff,
375 __be32 saddr, __be16 sport,
376 __be32 daddr, unsigned short hnum,
377 inet_ehashfn_t *ehashfn);
378
379struct sock *inet_lookup_run_sk_lookup(const struct net *net,
380 int protocol,
381 struct sk_buff *skb, int doff,
382 __be32 saddr, __be16 sport,
383 __be32 daddr, u16 hnum, const int dif,
384 inet_ehashfn_t *ehashfn);
385
386static inline struct sock *inet_lookup_established(struct net *net,
387 const __be32 saddr, const __be16 sport,
388 const __be32 daddr, const __be16 dport,
389 const int dif)
390{
391 return __inet_lookup_established(net, saddr, sport, daddr,
392 ntohs(dport), dif, sdif: 0);
393}
394
395static inline struct sock *__inet_lookup(struct net *net,
396 struct sk_buff *skb, int doff,
397 const __be32 saddr, const __be16 sport,
398 const __be32 daddr, const __be16 dport,
399 const int dif, const int sdif,
400 bool *refcounted)
401{
402 u16 hnum = ntohs(dport);
403 struct sock *sk;
404
405 sk = __inet_lookup_established(net, saddr, sport,
406 daddr, hnum, dif, sdif);
407 *refcounted = true;
408 if (sk)
409 return sk;
410 *refcounted = false;
411 return __inet_lookup_listener(net, skb, doff, saddr,
412 sport, daddr, hnum, dif, sdif);
413}
414
415static inline struct sock *inet_lookup(struct net *net,
416 struct sk_buff *skb, int doff,
417 const __be32 saddr, const __be16 sport,
418 const __be32 daddr, const __be16 dport,
419 const int dif)
420{
421 struct sock *sk;
422 bool refcounted;
423
424 sk = __inet_lookup(net, skb, doff, saddr, sport, daddr,
425 dport, dif, sdif: 0, refcounted: &refcounted);
426
427 if (sk && !refcounted && !refcount_inc_not_zero(r: &sk->sk_refcnt))
428 sk = NULL;
429 return sk;
430}
431
432static inline
433struct sock *inet_steal_sock(struct net *net, struct sk_buff *skb, int doff,
434 const __be32 saddr, const __be16 sport,
435 const __be32 daddr, const __be16 dport,
436 bool *refcounted, inet_ehashfn_t *ehashfn)
437{
438 struct sock *sk, *reuse_sk;
439 bool prefetched;
440
441 sk = skb_steal_sock(skb, refcounted, prefetched: &prefetched);
442 if (!sk)
443 return NULL;
444
445 if (!prefetched || !sk_fullsock(sk))
446 return sk;
447
448 if (sk->sk_protocol == IPPROTO_TCP) {
449 if (sk->sk_state != TCP_LISTEN)
450 return sk;
451 } else if (sk->sk_protocol == IPPROTO_UDP) {
452 if (sk->sk_state != TCP_CLOSE)
453 return sk;
454 } else {
455 return sk;
456 }
457
458 reuse_sk = inet_lookup_reuseport(net, sk, skb, doff,
459 saddr, sport, daddr, ntohs(dport),
460 ehashfn);
461 if (!reuse_sk)
462 return sk;
463
464 /* We've chosen a new reuseport sock which is never refcounted. This
465 * implies that sk also isn't refcounted.
466 */
467 WARN_ON_ONCE(*refcounted);
468
469 return reuse_sk;
470}
471
472static inline struct sock *__inet_lookup_skb(struct sk_buff *skb,
473 int doff,
474 const __be16 sport,
475 const __be16 dport,
476 const int sdif,
477 bool *refcounted)
478{
479 struct net *net = skb_dst_dev_net_rcu(skb);
480 const struct iphdr *iph = ip_hdr(skb);
481 struct sock *sk;
482
483 sk = inet_steal_sock(net, skb, doff, saddr: iph->saddr, sport, daddr: iph->daddr, dport,
484 refcounted, ehashfn: inet_ehashfn);
485 if (IS_ERR(ptr: sk))
486 return NULL;
487 if (sk)
488 return sk;
489
490 return __inet_lookup(net, skb, doff, saddr: iph->saddr, sport,
491 daddr: iph->daddr, dport, dif: inet_iif(skb), sdif,
492 refcounted);
493}
494
495static inline void sk_daddr_set(struct sock *sk, __be32 addr)
496{
497 sk->sk_daddr = addr; /* alias of inet_daddr */
498#if IS_ENABLED(CONFIG_IPV6)
499 ipv6_addr_set_v4mapped(addr, v4mapped: &sk->sk_v6_daddr);
500#endif
501}
502
503static inline void sk_rcv_saddr_set(struct sock *sk, __be32 addr)
504{
505 sk->sk_rcv_saddr = addr; /* alias of inet_rcv_saddr */
506#if IS_ENABLED(CONFIG_IPV6)
507 ipv6_addr_set_v4mapped(addr, v4mapped: &sk->sk_v6_rcv_saddr);
508#endif
509}
510
511int __inet_hash_connect(struct inet_timewait_death_row *death_row,
512 struct sock *sk, u64 port_offset,
513 u32 hash_port0,
514 int (*check_established)(struct inet_timewait_death_row *,
515 struct sock *, __u16,
516 struct inet_timewait_sock **,
517 bool rcu_lookup,
518 u32 hash));
519
520int inet_hash_connect(struct inet_timewait_death_row *death_row,
521 struct sock *sk);
522#endif /* _INET_HASHTABLES_H */
523

source code of linux/include/net/inet_hashtables.h